The present invention relates to an improved variable intake apparatus for a multi-cylinder internal combustion engine which can obtain a high intake air charging efficiency and a high output torque over a wide engine speed range of the internal combustion engine from low to high engine speed ranges.
Conventionally, various types of intake apparatuses have been proposed which are designed to make use of an intake air pressure-wave pulse generated in air intake passageways communicating with the respective cylinders of a multi-cylinder internal combustion engine, so as to obtain an extra charging effect by elevating the pressure at inlet ports of respective cylinders of the engine toward a latter half of an intake stroke in the respective cylinders.
For example, the length and/or volume of intake pipes is varied in response to the speed of an internal combustion engine so as to obtain an inertial supercharging effect and a resonance supercharging effect in supercharging intake air. With a suitable combination thereof, the intake air charging efficiency is highly maintained over a wide engine speed range from low to high engine speed ranges, whereby the output torque of the internal combustion engine is drastically improved.
In JP-A-63-159334, each cylinder of an intake apparatus has an air intake length switching means, and an air intake passageway area switching means respectively, so that the two switching means are selected according to the engine speeds.
In the intake apparatus, the construction of the intake apparatus is made complicated to disposed switching valves driven by the two switching means at required positions. Many components and high production costs are required because of the complicated construction of the intake apparatus.
It is an object of the invention to provide a simple and low-cost variable intake apparatus for a multi-cylinder internal combustion engine which can switch intake characteristics by a single air intake control valve.
In a first aspect of the invention, a variable intake apparatus for a multi-cylinder internal combustion engine including an air intake passageway 6 including a pair of air intake passageway portions communicating an intake air collecting chamber 5 with respective cylinders,
an intake air control valve 20 integrally provided with a plurality valve members at an opening 11 formed in a partition wall,
the partition wall being formed between the intake air collecting chamber 5, and
the intake air control valve 20 controls to open and close the one of the air intake passageway portions 61, 62 with one of the valve bodies 25, 26, and to open and close the opening 11 with the other of the valve bodies 25, 26.
In the first aspect, the single air intake control valve, which integrally has two valve bodies, simultaneously controls the opening/closing of one of the pair of the intake air passages and the opening/closing of an opening portion of a partition wall between the other of the pair of the intake air passages and the air intake collecting chamber according to rotation speeds to drive the single air intake control valve, to thereby control an air intake length and an air intake area, whereby an intake air charging efficiency is highly maintained over a wide engine speed range from low to high engine speed ranges and an output torque of a multi-cylinder internal combustion engine is drastically improved.
Further more, the construction of the air intake control valve is thus simplified by adopting the construction in which the pairs of valve bodies are provided on the single air intake control valve, and this serves to reduce the number of components involved, thereby making it possible to reduce the production costs.
In the second aspect of the invention, the variable intake apparatus according to claim 1, wherein the intake air control valve 20 controls to open and form the one of the air intake passageway portions 61, 62 with the one of the valve bodies 25, 26 at the same time that the intake air control valve 20 controls to close the opening 11 and form the one of the air intake passageway portions 61, 62 with the other of the valve bodies 25, 26.
By opening the one induction passage while closing the opening in the partition wall the air intake passageway area may be wider and the air intake passageway length may be longer, whereby the output torque in particular in the middle engine speed range, can be improved. As this occurs, a turbulent flow can be generated in an induction air flow by the valve body which opens the one air intake passageway and the atomization of fuel is promoted by the turbulent flow to thereby improve the combustion efficiency.
According to a third aspect of the invention, the variable intake apparatus according to claim 1, wherein the air intake passageway portions 61, 62 are formed to cover the circumference of the intake air collecting chamber 5.
The entirety of the intake manifold 4 can be made compact to thereby attain the miniaturization of the intake manifold 4. In addition, because the air intake control valve is provided in the air intake passageway 6 covering the circumference of the intake air collecting chamber 5 and in the opening 11 in the bulkhead formed along the intake air collecting chamber 5, not only is the air intake passageway 6 allowed to communicate directly with the downstream side of the air intake passageway but also the one air intake passageway is allowed to function as an intake air collecting chamber 5 through the pair of valve bodies of the air intake control valve, whereby the air intake passageway length, air intake passageway area and volume of the intake air collecting chamber 5 can be controlled to be switched over through the simple construction.